Was There a Sixth Prehistoric Mass Extinction?

Was There a Sixth Prehistoric Mass Extinction?

'Missing' disaster led to all-time worst extinction
by Jeff Hecht, Newc Scientist, October 23, 2014
http://www.newscientist.com/article/mg22429922.300-missing-disaster-led-to-alltime-worst-extinction.html

Have we missed a mass extinction? Extra catastrophic
event may have occurred 8 million years before the
‘Great Dying’, claim experts by Ellie Zolfgharifard,
Daily Mail, Oct. 23, 2014
http://www.dailymail.co.uk/sciencetech/article-2805194/Have-missed-mass-extinction-Extra-catastrophic-event-occurred-8-million-years-Great-Dying-claim-experts.html

The talk is:

Bond, D. P. G., Wignall, P. B., M. M. Joachimski,
and others, 2014, Catastrophic Middle Permian
Extinction and Extraordinary Recovery in High
Latitudes. Geological Society of America Abstracts
with Programs. vol. 46, no. 6, p.170,
https://gsa.confex.com/gsa/2014AM/webprogram/Paper241677.html
https://gsa.confex.com/gsa/2014AM/webprogram/Session35273.html

Yours,

Paul H.